EPIRB vs PLB: Which Beacon

What These Beacons Do

Both EPIRBs and PLBs serve the same fundamental purpose: when you're in a life-threatening emergency on the water, they transmit a distress signal via the Cospas-Sarsat satellite system that alerts rescue coordination centers worldwide. The signal includes your GPS position (on GPS-equipped models) and your registration information, which tells rescuers who you are, what your vessel looks like, and who to contact for additional information.

The difference is in the form factor, battery life, registration, and activation method — details that determine which beacon (or combination) is appropriate for your boating.

EPIRB: The Vessel Beacon

An EPIRB is a boat-mounted device, typically installed in a hydrostatic release bracket on deck. When the boat sinks, the hydrostatic release triggers at a depth of a few feet, freeing the EPIRB to float to the surface and activate automatically. It can also be activated manually. Once triggered, it transmits continuously for at least 48 hours — long enough for rescue services to locate and reach you even in remote waters.

EPIRBs are registered to the vessel with NOAA. The registration includes boat description, owner information, emergency contacts, and operational details. This means rescue services know what boat to look for, how many people might be aboard (from the registration), and who to call for additional information — before they even leave the dock.

The 48-hour battery life is significant for offshore boating where rescue may take time. In remote ocean areas, it can take 12–24 hours for a rescue asset to reach your position. The EPIRB's extended transmission window ensures the signal is still broadcasting when help arrives, and allows rescuers to home in on the signal during the final approach.

PLB: The Personal Beacon

A PLB is a compact, pocket-sized device that a person carries. It activates manually — there's no hydrostatic release because it's designed to be on your person, not mounted to a sinking vessel. Battery life is at least 24 hours of continuous transmission. PLBs are registered to the individual rather than a vessel, which means your registration follows you regardless of which boat you're on.

The personal registration is a key advantage for boaters who use multiple boats, charter, or crew on other people's vessels. Your PLB works on any boat, any kayak, or even on land — the rescue system doesn't care where you activate it, only that you need help and here's your GPS position.

Size is the other advantage. PLBs fit in a PFD pocket, a tackle bag, or a jacket. You can carry one without any installation, mounting, or modification to the boat. For kayakers, small-boat sailors, and anyone who might be separated from their vessel in an emergency, a PLB on your person is more reliable than an EPIRB on a boat that's no longer under you.

Head to Head

Battery Life

EPIRB: 48+ hours. PLB: 24+ hours. For offshore passages where rescue may be distant, the EPIRB's longer transmission window provides a larger safety margin. For nearshore boating where Coast Guard response is measured in hours rather than days, the PLB's 24 hours is more than adequate.

Activation

EPIRB: automatic (hydrostatic release) or manual. PLB: manual only. Automatic activation is critical for scenarios where you can't activate a beacon yourself — sudden capsizing, incapacitation, or nighttime sinking. A hydrostatic-release EPIRB works even if every person aboard is unconscious or in the water.

Cost

EPIRBs with GPS and hydrostatic release: $$–$$$. PLBs with GPS: $–$$. PLBs are significantly less expensive, which makes it practical to equip every person on board rather than relying on a single vessel-mounted device.

Registration

EPIRB: registered to vessel. PLB: registered to person. Both require free NOAA registration. Keep registration current — outdated registration information wastes rescue time and resources.

Testing and Maintenance

Both EPIRBs and PLBs have built-in self-test functions that verify battery condition and internal circuit function without transmitting a distress alert. Run the self-test monthly — it takes seconds and confirms the unit is operational. The self-test LED provides a green/red indication: green means the unit is ready, red or no response means service or battery replacement is needed.

The Layered Approach

The most robust safety setup combines both: an EPIRB mounted on the vessel with hydrostatic release (covers automatic activation if the boat sinks) and a PLB on each person aboard (covers separation from the vessel, individual man-overboard scenarios, and provides redundancy if the EPIRB fails). This is standard practice for offshore racing, commercial fishing, and long-distance cruising.

For nearshore recreational boating where the Coast Guard is within VHF range, a PLB alone provides excellent personal protection at a fraction of the EPIRB's cost. The deciding factor is how far offshore you go and how quickly rescue can reach you.